[librdmacm,8/8] Open files with "close on exec" flag

Commit Message

Yann Droneaud July 16, 2013, 9:59 p.m. UTC

File opened by librdmacm are not supposed to be inherited across
exec*(), most of the files are of no use for another program, and
others cannot be used without the associated memory mapping.

This patch changes fopen() open() and socket() to always set
close on exec flag.

This patch also add checks to configure to guess if fopen() supports
"e" flag. If O_CLOEXEC and SOCK_CLOEXEC are supported, fopen() should
support "e". If not supported, its discarded according to POSIX. Many
operating systems have support for fopen("e").

You might find more information about close on exec in the following articles:

- "Excuse me son, but your code is leaking !!!" by Dan Walsh
  http://danwalsh.livejournal.com/53603.html

- "Secure File Descriptor Handling" by Ulrich Drepper
  http://udrepper.livejournal.com/20407.html

Note: this patch won't set close on exec flag on file descriptors
created by the kernel for completion channel and such.
This is addressed by another kernel patch.

Signed-off-by: Yann Droneaud <[e-mail]>
---
 configure.ac | 24 ++++++++++++++++++++++++
 src/acm.c    |  4 ++--
 src/cma.c    |  2 +-
 3 files changed, 27 insertions(+), 3 deletions(-)

Patch

diff --git a/configure.ac b/configure.ac
index 807470f..31b1a0e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -78,6 +78,30 @@  AC_CHECK_HEADER(infiniband/acm.h,
 		AC_DEFINE(DEFINE_ACM_MSG, 1, [adding ACM message definition]),
 			[#include <infiniband/acm.h>]), [])
 
+dnl Checks close on exec support
+AC_CHECK_HEADERS([fcntl.h sys/socket.h])
+
+AC_CHECK_DECLS([O_CLOEXEC],,[AC_DEFINE([O_CLOEXEC],[0], [Defined to 0 if not provided])],
+[[
+#ifdef HAVE_FCNTL_H
+# include <fcntl.h>
+#endif
+]])
+AC_CHECK_DECLS([SOCK_CLOEXEC],,[AC_DEFINE([SOCK_CLOEXEC],[0],[Defined to 0 if not provided])],
+[[
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+]])
+
+AC_CACHE_CHECK(for close on exec modifier for fopen(), ac_cv_feature_stream_cloexec_flag,
+   [if test $ac_cv_have_decl_O_CLOEXEC = yes ; then
+        if test $ac_cv_have_decl_SOCK_CLOEXEC = yes ; then
+            ac_cv_feature_stream_cloexec_flag="e"
+        fi
+    fi])
+AC_DEFINE_UNQUOTED([STREAM_CLOEXEC], "$ac_cv_feature_stream_cloexec_flag", [fopen() modifier for setting close on exec flag])
+
 AC_CACHE_CHECK(whether ld accepts --version-script, ac_cv_version_script,
     if test -n "`$LD --help < /dev/null 2>/dev/null | grep version-script`"; then
         ac_cv_version_script=yes
diff --git a/src/acm.c b/src/acm.c
index c9ca5b5..6e8e173 100644
--- a/src/acm.c
+++ b/src/acm.c
@@ -80,7 +80,7 @@  static int ucma_set_server_port(void)
 {
 	FILE *f;
 
-	if ((f = fopen("/var/run/ibacm.port", "r"))) {
+	if ((f = fopen("/var/run/ibacm.port", "r" STREAM_CLOEXEC))) {
 		fscanf(f, "%hu", (unsigned short *) &server_port);
 		fclose(f);
 	}
@@ -100,7 +100,7 @@  void ucma_ib_init(void)
 	if (!ucma_set_server_port())
 		goto out;
 
-	sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	sock = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, IPPROTO_TCP);
 	if (sock < 0)
 		goto out;
 
diff --git a/src/cma.c b/src/cma.c
index 2fb9913..baebecd 100644
--- a/src/cma.c
+++ b/src/cma.c
@@ -328,7 +328,7 @@  struct rdma_event_channel *rdma_create_event_channel(void)
 	if (!channel)
 		return NULL;
 
-	channel->fd = open("/dev/infiniband/rdma_cm", O_RDWR);
+	channel->fd = open("/dev/infiniband/rdma_cm", O_RDWR | O_CLOEXEC);
 	if (channel->fd < 0) {
 		fprintf(stderr, PFX "Fatal: unable to open /dev/infiniband/rdma_cm\n");
 		goto err;